It’s been one of the greatest mysteries in the residential world for three years: Who was the buyer behind the city’s most expensive closed residential deal, the $100.5 million penthouse at One57?

The code – no pun intended – has now been cracked. It is Michael Dell, founder and CEO of Dell Technologies, according to the Wall Street Journal. The nine-figure deal puts the technology mogul in a club of one – until far pricier deals at 220 Central Park close.

The sale at the Extell Development property was announced in May 2012, but closed in December 2014, city records show, at about $9,200 a foot. Department of Buildings filings spotted by the Journal show that Dell tapped Miró Rivera Architects to oversee a renovation of the 10,923-square-foot penthouse, which spans the 89th and 90th floors. The deal broke a 2012 record set by the $88 million purchase of Sanford Weill’s 15 Central Park West penthouse in 2012 by fertilizer tycoon Dmitry Rybolovlev’s daughter, Ekaterina Rybolovleva.

Dell, 52, has a net worth of $23.3 billion, according to Forbes. Earlier this month, he confirmed chatter that he was considering taking Dell Technologies public again, after going private in 2013. Dell’s private investment firm, MSD Capital, is an active real estate investor, backing projects such as Sharif El-Gamal’s 45 Park Place and picking up stakes in properties such as Grand Central Terminal. And Dell is no stranger to fancy personal real estate either. In November, he entered contract to buy a penthouse at what will become Boston’s tallest residential tower. That deal, too, could set a new record in the city. He also owns the so-called Raptor Residence in Hawaii, a three-lot property recently assessed at $64.7 million.

Leighton Candler represented Dell in the One57 deal, according to the newspaper. That gives the Corcoran Group broker the distinction of handling the city’s record sale, though the deal is expected to be topped by one or more deals at Vornado Realty Trust’s 220 Central Park South. A penthouse there is reportedly in contract to sell for over $200 million to hedge funder Ken Griffin.

It’s apt that Dell has been outed now. Tomorrow is his birthday. [WSJ] — Hiten Samtani